Gas turbine engines may be used to power various types of vehicles and systems, such as air or land-based vehicles. In typical gas turbine engines, compressed air generated by axial and/or radial compressors is mixed with fuel and burned, and the expanding hot combustion gases are directed along a flowpath toward a turbine. The turbine includes a turbine nozzle having stationary turbine vanes, and the gas flow deflects off of the vanes and impinges upon turbine blades of a turbine rotor. A rotatable turbine disk or wheel, from which the turbine blades extend, spins at high speeds to produce power. Gas turbine engines used in aircraft use the power to draw more air into the engine and to pass high velocity combustion gas out of the gas turbine aft end to produce a forward thrust. Other gas turbine engines may use the power to turn a propeller or an electrical generator.
Gas turbine engines typically operate more efficiently with increasingly hotter air temperature. The materials used to fabricate the components of the turbine, such as the nozzle guide vanes and turbine blades, typically limit the maximum air temperature. In current gas turbine engines, the turbine blades are made of advanced single crystal nickel-base superalloys such as, for example, CMSX4, SC180, Rene N6, and PWA1484, etc. These materials exhibit good high-temperature strength; however, the high temperature environment within a turbine can cause, among other things, creep, oxidation, and/or thermal fatigue of the turbine blades and nozzles made of these materials. Coatings are commonly employed to significantly improve the resistance of the single-crystal alloys to oxidation and hot corrosion.
For turbine blade applications it is desirable to have single crystal nickel-base superalloys having high-temperature creep strength (normalized by density) that is superior to already-known single crystal nickel-base superalloys. Lower density single crystal superalloy turbine blades reduce the stress on the turbine disk and/or enable the turbine to operate at higher speeds. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.